clement



Re. 11,142 M Nov. 20; 1928.

E. E. CLEMENT RADIO BROADCAST SELECTING AND DISTRIBUTING SYSTEM Original Filed Feb. 29, 1924 3min ml f kw Qok Puklum Reissued Nov. 20, 1928.

UNITED STATES .Re.17,14z

PATENT- OFFICE.

EDWARD E. CLEMENT, or WASHINGTON, DISTRICT or CO UM IA, ASSIGNOR T0 EDWARD r. COLLADAY, or WASHINGTON, DISTRICT OF COLUMBIA.

RADIO DRonDoAsT SELECTING AND DISTRIBUTING sYsTDiu.

Original No. 1,522,361, dated January 6, 1925, Serial No. 696,076, filed February 29, 1924. Application for reissue fi1ed Janua1-y 5, 1927. Serial No. 159,249.

My invention relates to systems of radio.

broadcast distributionand is an improvement in the system described and claimed in my prior copending application, filed August 14, 1922, SerialNo. 581,829 patented January (5, 1925, as Patent No. 1,522,357.

The present invention has for its object to provide improved centralized means for receiving from primary or distant stations and relaying the same modulations to, sub scribers in a local area, or in other words, an improvement in collecting and regional distribution. 1 attain my ob ect by employing a superheterodyne receiving circuit, and retransmitting on the beat wave, for reception in the local area, this in combination with simultaneous supervision, 1 control, metering, etc, of the service thus rendered, over wired circuitsto the subscribers stations, all as in the aforesaid prior copending application. At each subscribers sta-- tion I locate. a receiving set which may be. fed with. direct current over the subscribers wired line circuit, and said receiving set may be of any desired type, provided the construction and adjustment of all the subscribers sets is standard and uniform, so that they are tuned once for all to the same wave length, being the heat wave length transmitted from the local central station relay transmitter.

My invention is illustrated in the accompanying drawing, in which the figure is a diagram showing a central station, a subscribersstat-ion and the line circuit interconnecting them) i I Referring to the drawing, C is a central station containing a telephone switchboard and a radio switchboard,.each with connectiveapparatus and containing multiple [line terminals for the subscribers telephone line 16-17 which extends to the subscribers station A, where a standard telephone instru-. ment set is connected as. shown. Tapped oil from the wire 17 is a loop containing the windings of a relay L shunted by a condenser. This relay controls the normal connection of wires 52 and 53 to the line wires 16-17, and also controls the normal connection of a companion relay L to the line wire 16, which is the tip wire of the pair.

The relay, L in turn controls output terminals of the radio detector set 36", which are normally retracted so as to connect the his radio set across the line l6-17, so that the operator at the radio switchboard can listen in overthe line and ascertain if the central olfice heat wave is in tune with and is being properly received by the subscribers instrument 36 The relay L is controlled by the radio switchboard operator by means of the key Km, connected to the plug circuit Pm. When the plug of this circuit is inserted in the subscribers jack at m, a busy tone test is put on the multiple or test thimble of the line on the telephone switchboard, battery B is connectedto the cut-off relay w, the operators headset is bridged across the conductors l617, and finally key'Kw being closed, battery B throws current out-on the tip side ofthe line 16 to energize relay L and enable the operator to listen in on the subscribers radio set. \Vhile I have shown the subscribers receiving telephone cut off during this operation, it may remain connec-ted the. cut-oii' being an additional fea ture which enables the central office to de prive the subscriber of all service in case of necessity. NVhen the operator is satisfied, and desires to be disconnected from the I line the key K00 is opened, and if desired the nects thesubscribers phone 36, and connects be continued at the subscribers station in the ordinary way. Incoming telephone calls from the station A and answered outgoing calls resulting from telephone operators plugging in asat jack mflresult in energizing 'relay L, which displaces relayQL? and totally disconnects the radio detector set 36 from the I line 16'17, this condition being maintained as long as the line is inuse for conversation.

Radio transmitter T comprises an antenna circuit 1, coupler 2, local oscillator circuit 3, the first detector l, radio amplifying units 5 and 6, and a radiating circuit 7. Since the essential part of the heterodyning 'oper ation is in the elements 1, 2, 3, a, it is to be understood that the arrangement of the amplifying andother stages between the first detector 4 and the radiating circuit 7 are subject to modification in accordance with good practice. The beat wavesafter being sufi'iciently amplified may be directly thrown upon the radiating circuit, or may be communicated through a modulator and osc llator circuit, by which increasedenergy may be imparted to the radiating beat frequency waves. In the first case energy may be communicated'in sufiicient quantity by the oscillator 3, the tubes, 5 and 6 being essentially power tubes and operatingon any desired voltage. In thesecond case the result Wlll bethe transmission of a doubly modulated carrier wave, and the subscribers instrument 36 will thenbe provided with double demodulating' means of any known or suitable type.

The important point in the present invention is this: to select different stations and receive. from any distant station at any wave length, or frequency, v heterodyning. by means v of the localwoscillator 3 with said incoming modulated waves, and by proper tuning of the, oscillator circuit 3 always producing a standard beat wave to which the subscribers instruments in the local area are permanent- 1y Wllfid. The. first and most important ancillary feature is that already described,

of listening in from $1 central. station by th radio operator over the 'subscribers telephone line or other wired circuit, so as to be able toproperly adjust and tune the central oflic e"' instrument to the su-bscribers s anda W length. I

1; A v broadcasting vsystem comprising primary high Po s a srsi g different Wave, lengths, secondary stations having receiving radio sets tunable to the different primary wave lengths and also having relay transmitting apparatus controlled by the receiving sets and operating on a standard fixed wave length the same. for, all secondary :transmitters, and subscribers? receiving radio stations grouped around each secondary transmitting station in its local area and tuned permanently tothe fixedjtransmitting wave lengths thereof, the receiving radio sets at the secondary or relay stations each comprising a tuned circuit for receiving the rimary modulatedwaves, and a local osciltor circuit tunable to: furnish heterodyning wavesfsuch that modulated beat waves will always be produced and fed into the transcircuit. at the standard local fre- 2, Aradlo s stem of lntercommunlcation a plura ity of standardized uniform receiving stations divided into, groups, all

said stations being tuned to one common frequency and f sensitivene mit d to the areas covered by their. respective groups,

lQQal tran mitt ng S t on. fo each group o king on ai c mmon wav I n 1 and. means. formod l t ngthe wa s a. ated from said transmitting stations as de- In either case the beat wave is of 1 Standard frequency.

terniined by primary stations using variable wave lengths, said means comprislng a 'primary circuit'tunable to the wave lengths of the primary stations, and a local oscillator circuit tunable to furnish heterodyning waves therefor, so asto always. maintain the beat wave in'the transmitting circuit at the common or standard wave length for the loCalgroup. r

3. A broadcasting system comprising a primary station, a secondary distributing station, and a plurality of local receiving stations; related to the secondary station and all in permanent tune therewith, means at said secondary station to receive broadcast waves from the primary station at its wave length, and to relay and redistribute the same in its own area at the standard wave length to which its receiving stations are tuned, and means also at said secondary stati on todeterinine when its transmitter is actually tuned to the fixed wave length of its I tions in a local area permanently tuned to a fixed wave length, which comprises receiving any one. of the primary waves, changing the frequency of the received wa've by amounts depending upon the particular wave received top'roduce' a wave alwaysthe same and correspending in wave length to that of the recei'ving' stations, and transmitting the wave at the changed frequency to the "receiving ta ien V y I 5, The method of distributing broadcast matter toa plurality of receiving stations perman'ently tuned to a fixed wave length which comprises, receiving broad'castmatter on va-' rious wave lengths different from the fixed wavelength of the receiving station, heterodyning the received wavewith a second'wave, ad'iusting'the frequency of the second wave to produce a constant frequency beat wave corresponding in wave' length to the fixed wave len thjof the receiving stations, and transmittingsaijd beat wave to the receiving stations.

6- T me hod 1: dia ib ang m das matter toa plurality of receiving stations permanently tuned to a fixed wave length which comprises, receiving broadcast matter on various wavelengths'diflerent from the fixe W v length of th r e ving n,

'heterodyningtlie receiyed wavewith a sec ond wayeradjusting the frequency of the second wave to produce a constant frequency heat wave corresponding in wave length to the fixed Wave length of the receiving stations, and amplifying and radiating said ea-t wave to the receiving stations.

7. The method of distributing broadcast matter to a. plurality of receiving stations permanently tuned to a fixed wave length which comprises, receiving broadcast matter on various wave lengths different from the fixed wave length of the receiving station, heterodyning the received wave with a second wave,

adjusting the frequency of the second wave to produce a constant frequency beat wave corresponding in wave length to the fixed wave length of the receiving stations, amplifying and radiating said beat wave to the receiving stations, detecting the beat Wave at the receiving stations, and returning detected current to the relay station to determine if the beat wave is properly adjusted in frequency.

8. The method of broadcast distribution which comprises primarily transmitting broadcast matter by radiation over a common area at different wave lengths, and relaying the broadcast matter in different local areas to a plurality of receiving stations in each local area at a frequency common to all the receiving stations, said relaying being accomplished by means of a heterodyning wave adjustableto beat any incoming wave and thereby to produce a constant frequency for transmission to said receiving stations.

9. The method of broadcast distribution which comprises receiving broadcast matter at each of aplurality of relay stations at any one of a plurality of different wave lengths and retransmitting the received broadcast matter from each such relay station to a plurality of receiving stations grouped about it in a local area on a frequency common to all the receiving stations of a group, said retransmitting being accomplished by means of a heterodyning wave adjusted to beat any of the various incoming waves and produce a constant frequency for transmission to said receiving stations.

10. The method of broadcasting intelligence which consists in radiating high power electromagnetic waves for long distances over a large area at different wave lengths, transforming energy so radiated to a plurality of separated points within the large area into low power electromagnetic waves of a definite fixed wave length the same for all the received Waves at any one point, and reradiating said transformed waves over smaller areas within said large area, said reradiated waves being produced by means of a heterodyning wave adapted to beat any incoming wave and produce a. constant frequency only for transmission to said receiving stations.

11. The method of broadcasting intelligence which consists in radiating high power electromagnetic waves from a plurality of primary stations by short wave carriers having an identifying energy characteristic for each primary station, receiving the energy so radiated at a secondary station for relay transmission to a group of receiving stations local to the secondary station, changing the received energy into low power carrier waves having an identifying energy characteristic the same for all of the receiving stations of a group and retransmitting the changed wave at low power over a. small area including said group of stations, said change of energy being accomplished by means of a heterodyning wave adapted to beat any of the various incoming waves and to produce a constant frequency only for transmission to said receiving stations.

12. The method of broadcast distribution to a plurality of receiving stations in agiven area tuned to a common fixed wave length which comprises primarily transmitting broadcast matter by radiation over said area at various different wave lengths, and relaying the broadcast matter to the said receiving stations by receiving waves atone of said wave lengths, heterodyning the received wave wit-ha second wave, adjusting the frequency of the second Wave until regardless of the frequencyof the received wave, the heat wave always corresponds in wave length to the said common fixed wave length and transmitting said beat wave to the receiving stations.

In testimony whereof I hereunto aflix my signature;

I EDWARD E. CLEMENT. 

